Saturday, February 2, 2008

Cutting Gears

This morning I went out and machined the teeth on a couple pinions. This is the last two of twenty three gears required for the model steam shovel presently under construction. These two will work in unison to push the dipper stick out and in.

I do not know how many viewers of this blog machine their own gears, but it is not a difficult task. When you look at all the charts, tables, math, etc. it is scary. But I have taken the attitude that if the early settlers could make working gears for their grist mills and sawmills, etc. by pounding pegs in a log, then shame on me if I cannot make a gear on my milling machine. Over time I have collected a few commercial gear cutters, and they are nice, but most of the time I do not have the right one and end up grinding a lathe tool bit for a single tooth cutter. You can use a gear of the same pitch and very near the same number of teeth as a template to fit the cutter bit to. Most often I make a layout using the drafting table, and grind a bit to fit my layout. The small paint brush is wetted with cutting oil and held next to the cutter so the bit wipes through the brush providing a film of lubrication each round. It is a lot cleaner than a flood system, for such little jobs.

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